Co-deposition of Ni-Co alloys on carbon steel and corrosion resistance

Ni-co alloys were synthesized on carbon steel by electrodeposition method using electrolytes with different ni2+ concentrations. the co-deposition phenomenon of ni-co alloys was described as anomalous behavior. morphology and microstructure were investigated by scanning electron microscope and xrd analysis and correlated with ni/co ratio in plating bath. both granular crystals and smooth surface morphology were illustrated with sem micrographs,and a combination of fcc and hcp structure were characterized by xrd patterns which depended strongly on cobalt content in the deposit. the electrochemical properties of ni-co alloy coatings were evaluated in 3% nacl solution by means of potentiodynamic polarization and electrochemical impedance spectroscopy (eis).a better corrosion resistance was obtained with rich nickel deposit.